My 660 has been working hard lately getting ground sprayed and worked up for planting. While planting several acres of corn with a fairly heavy no-till planter, I noticed the lift was slowing down a bit. I finished up the corn, hooked up a disc, and it was bobbing (hiccups). I started working ground for sorghum. By the time I finished, the disk wouldn't raise enough to clear the ground. Fluid level is full.
Today, I pulled the piston pump plug and verified prime at the pump. With the disk hooked up, i removed the fill cap and watched the lift cylinder with a flashlight as I attempted to raise the disk with touch control. Oil sprayed from above and behind the cylinder in the area of the safety valve which I suspect is the culprit. This, if the only issue, would be the second safety valve failure in 12 years, the last being 6 or 7 years ago. Is that normal? I notice, despite living under shelter, the UC 134 fluid has become milky from condensation. Could that raise the pressure and blow the valve?
The FO-20 manual doesn't show and I don't recall a gasket between the lift cylinder and lift cover, just o'rings between accessory plate and cylinder. Is there a gap between the cylinder and lift cover at the location of the safety valve which allows fluid to discharge back to the sump as I observe, presumably oriented with the side holes in the safety valve? I think so from prior experience.
I am planning to pull the lift cover, drain the milky 134 fluid, rinse with kerosene, and replace the safety valve and accessory plate orings.
I would also mention when I first used the tractor this Spring, I had no lift as the pump had lost prime. I was able to get it primed by holding my thumb over the pump prime hole while cranking and all has been fine until now. Unrelated?
Stopping at CNH for parts in the morning and looking for confirmation on the path I'm taking. I have a lift cover gasket on hand from a prior entry when I tuned up the unit with Zane's jig, replaced the cam follower pin, etc..
Today, I pulled the piston pump plug and verified prime at the pump. With the disk hooked up, i removed the fill cap and watched the lift cylinder with a flashlight as I attempted to raise the disk with touch control. Oil sprayed from above and behind the cylinder in the area of the safety valve which I suspect is the culprit. This, if the only issue, would be the second safety valve failure in 12 years, the last being 6 or 7 years ago. Is that normal? I notice, despite living under shelter, the UC 134 fluid has become milky from condensation. Could that raise the pressure and blow the valve?
The FO-20 manual doesn't show and I don't recall a gasket between the lift cylinder and lift cover, just o'rings between accessory plate and cylinder. Is there a gap between the cylinder and lift cover at the location of the safety valve which allows fluid to discharge back to the sump as I observe, presumably oriented with the side holes in the safety valve? I think so from prior experience.
I am planning to pull the lift cover, drain the milky 134 fluid, rinse with kerosene, and replace the safety valve and accessory plate orings.
I would also mention when I first used the tractor this Spring, I had no lift as the pump had lost prime. I was able to get it primed by holding my thumb over the pump prime hole while cranking and all has been fine until now. Unrelated?
Stopping at CNH for parts in the morning and looking for confirmation on the path I'm taking. I have a lift cover gasket on hand from a prior entry when I tuned up the unit with Zane's jig, replaced the cam follower pin, etc..